/*
#include<iostream>
#include<cmath>

using namespace std;

int main()
{
	int x1,x2,y1,y2,k;
	cin >> x1 >> y1 >> x2 >> y2 >> k;
	double ab=sqrt(pow(x1-x2,2)+pow(y1-y2,2));
	
	
	
	cout << k*ab/(k-1) << endl;
	
	return 0;
	
}
*/

/*
#include<bits/stdc++.h>
using namespace std;

int main(){
    double x1,x2,y1,y2,k,r,ac,ab;
    cin >> x1 >> y1 >> x2 >> y2 >> k;
    ab=pow((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2),0.5);
    ac=k*ab/(k+1);
    r=pow(k*k*(pow(x1-x2,2)+pow(y1-y2,2)),0.5)/(k*k-1);
    printf("%lf",ac+r*2);
    return 0;
}
*/

/*
#include<iostream>
#include<cmath>
#define PI 3.1415926535

using namespace std;

int main()
{
	double x1,x2,y1,y2,w,k;
	cin >> x1 >> y1 >> x2 >> y2 >> w >> k;
	double ab=sqrt(pow(x1-x2,2)+pow(y1-y2,2));
	double d=ab/(k+1)+ab/(k-1);
	
	double c1_x=(x1+x2)*k*1.0/(k+1);
	double c1_y=(y1+y2)*k*1.0/(k+1);
	double c2_x=(x1+x2)*k*1.0/(k-1);
	double c2_y=(y1+y2)*k*1.0/(k-1);
	
	double mid_x=(c1_x+c2_x)/2;
	double mid_y=(c1_y+c2_y)/2;
	
	if(w>=mid_y&&w<mid_y+d/2)
	{
		double t=mid_y+d/2-w;
		double jiaodu=acos((d/2-t)/(d/2));
		
		printf("%lf",jiaodu/PI);
	}
	else if(w>mid_y-d/2&&w<mid_y)
	{
		double t=mid_y-w;
		double jiaodu=acos(t/(d/2));
		
		printf("%lf",1-jiaodu/PI);
	}
	else if(w>=mid_y+d/2)
	{
		printf("1.000000");
	}
    else if(w<=mid_y-d/2)
    {
        printf("0.000000");
    }
	return 0;
	
}

*/

#include<bits/stdc++.h>
using namespace std;

int main(){
    double x1,x2,y1,y2,k,r,w,y;
    cin >> x1 >> y1 >> x2 >> y2  >> w >> k;
    r=pow(k*k*(pow(x1-x2,2)+pow(y1-y2,2)),0.5)/(k*k-1);
    y=(k*k*y2-y1)/(k*k-1);
    if(y>w){
        if(w<=y-r){
            cout << "1.000000";
            return 0;
        }
        double d=y-w;
        printf("%lf",1-acos(d/r)/3.1415926);
    }else if(y < w){
        if(w>=y+r){
            cout << "0.000000";
            return 0;
        }
        double d=w-y;
        printf("%lf",acos(d/r)/3.1415926);
    }else{
        cout << "0.500000";
    }
    return 0;
}












